Up until about 100 years ago everyone thought that the universe was fixed and unchanging.

Then along came Mr Edwin Hubble who’s observations using the Mount Wilson telescope discovered that there were lots of galaxies beyond our own and that they were all moving away from one another as revealed by the Red Shift Doppler effect i.e. that the universe is expanding which means that it had a beginning

- The BIG BANG!

Scientists estimate the big bang was 14 billion years ago when the universe exploded into existence and started its expansion.

Now the Big Bang is not like an explosion you would imagine it, because it is not matter that is exploding but that it is the Space that is expanding.

It is like we are on the surface of a balloon that is expanding, so the other galaxies are moving away from us, and the further away an object is the greater is its speed as the more the universe expands the larger the balloon becomes so the greater the rate of expansion.

So again it is SPACE that is expanding.

Which also means that one day the universe will die, probably a trillion years from now the space will have expanded by so much that all of the galaxies and stars will have expanded away and eventually even the space between individual atoms will expand so that there will be nothing.